Mobile machine track shoe

ABSTRACT

A mobile machine track shoe includes a ground engaging surface including a first grouser bar and a second grouser bar substantially parallel to the first grouser bar. The track shoe further includes a base opposite the ground engaging surface. The base includes a first relief disposed opposite the first grouser bar, and a second relief disposed opposite the second grouser bar.

TECHNICAL FIELD

The present disclosure relates generally to the undercarriage of amobile machine and, more particularly, to a track shoe for a mobilemachine.

BACKGROUND

A track type mobile machine utilizes tracks on either side of themachine that are connected to ground engaging elements known as trackshoes to move the machine. Specifically, a sprocket driven by an engineof the machine engages links of the track to translate the track aboutspaced apart pulley mechanisms. As the track translates about the pulleymechanisms, connected track shoes engage a work surface under themachine to transmit torque from the sprocket to the surface in adirection opposite the desired travel direction of the machine, therebypropelling the machine.

A known track shoe is discussed in U.S. Pat. No. 4,805,968 (“the '968patent”) to Connerley, issued on Feb. 21, 1989. The '968 patent teachesa track shoe for a construction vehicle having a ground-contactingportion, a substantially flat body portion, and a grouser extendingtransversely across a width of the track shoe. The '968 patent explainsthat the grouser provides strength to the track shoe, and increasestraction between the track shoe and the ground to assist in moving thevehicle. The track shoe taught in the '968 also includes a plurality ofribs reinforcing the body portion along a length of the track shoe.

Such known track shoes, however, suffer from a variety of drawbackshindering the performance of the associated mobile machine. Forinstance, such track shoes are generally formed from standard low carboncontent steels and/or other like materials. While such materials aremore ductile (i.e., less brittle) than materials having a greater carboncontent, such materials may be more prone to wear, thereby reducing theuseful life of the track shoe and increasing the maintenance costsassociated with the mobile machine.

Track shoes made from such materials may also be relatively heavy, andsince mobile machines employ tracks having a large number of trackshoes, the track shoes make up a significant percentage of the overallmass of the undercarriage. Accordingly, utilizing such relatively highmass track shoes adversely affects fuel consumption of the mobilemachine, further increasing operating costs. The relatively high mass ofsuch track shoes also makes replacing and/or repairing such track shoesmore cumbersome.

The disclosed track shoes are directed to overcoming one or more of theproblems set forth above.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the present disclosure, a mobile machinetrack shoe includes a ground engaging surface including a first grouserbar and a second grouser bar substantially parallel to the first grouserbar. The track shoe further includes a base opposite the ground engagingsurface. The base includes a first relief disposed opposite the firstgrouser bar, and a second relief disposed opposite the second grouserbar.

In another exemplary embodiment of the present disclosure, a track shoefor a mobile machine includes a ground engaging surface. The groundengaging surface includes first and second substantially planar flats, afirst grouser bar disposed between a trailing edge of the track shoe andthe first flat, and a second grouser bar disposed between the first andsecond flats. The ground engaging surface also includes a third grouserbar disposed between the second flat and a leading edge of the trackshoe. The first and third grouser bars are spaced substantially equallyfrom the second grouser bar. The track shoe also includes a baseopposite the ground engaging surface. The base includes a first reliefdisposed opposite the first grouser bar, and a second relief disposedopposite the second grouser bar and substantially parallel to the firstrelief. In addition, the track shoe includes steel having a carboncontent greater than approximately 0.3%.

In a further exemplary embodiment of the present disclosure, a trackshoe for a mobile machine includes a ground engaging surface including afirst grouser bar, a second grouser bar substantially parallel to thefirst grouser bar, and a third grouser bar substantially parallel to thesecond grouser bar. At least one of the first, second, and third grouserbars has a height less than approximately 26 mm, and a width betweenapproximately 12.6 mm and approximately 14.2. A combined width of thefirst, second, and third grouser bars comprises approximately onequarter of an overall length of the track shoe. The track shoe alsoincludes a base opposite the ground engaging surface. The base includesa first relief and a second relief substantially parallel to the firstrelief. The first relief includes a first radius and the second reliefincludes a second radius less than the first radius. In addition, acenterline of the first grouser bar is collinear with a centerline ofthe first relief and a centerline of the second grouser bar is collinearwith a centerline of the second relief.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial illustration of an exemplary mobile machine;

FIG. 2 is an isometric view of an exemplary track shoe; and

FIG. 3 is a side elevation view of the exemplary track shoe shown inFIG. 2.

DETAILED DESCRIPTION

FIG. 1 illustrates a track type mobile machine 10 having a power source14 driving a tracked undercarriage 12. Mobile machine 10 may be amachine that performs an operation associated with an industry such asmining, construction, farming, or any other industry known in the art.For example, machine 10 may be an earth moving machine such as a dozer,a loader, an excavator, or any other earth moving machine.

Power source 14 may drive the tracked undercarriage 12 of machine 10 ata range of output speeds and torques. Power source 14 may be an enginesuch as, for example, a diesel engine, a gasoline engine, a gaseousfuel-powered engine, or any other suitable engine. Power source 14 mayalso be a non-combustion source of power such as, for example, a fuelcell, a power storage device, or any other source of power known in theart.

Tracked undercarriage 12 may include tracks 20 (only one shown inFIG. 1) driven by power source 14 via sprockets 16 (only one shown inFIG. 1). Each track 20 may include a chain 22 with attached groundcontrol devices called track shoes 24. Each chain 22 may comprise aplurality of chain links 29 connected to each other by rod assemblies25. Sprockets 16 may engage and transmit a torque to rod assembly 25 tothereby move the chain 22 about spaced apart pulley mechanisms 27. Eachchain link 29 may include two opposing sides, and each side may includetwo track links. In an exemplary embodiment, at least two such tracklinks may be connected to each track shoe 24, and in further exemplaryembodiments, the two track links on each opposing side of the chain link29 (four track links total) may be connected to each track shoe 24. Thetrack shoe 24 may be joined to such track links by way of a plurality ofthreaded fasteners (not shown), corresponding thru holes 30 (FIG. 3)formed in the track shoe 24, and threaded holes (not shown) formed inthe track links. That is, each track shoe 24 may be joined to tracklinks by cap screw-type fasteners, bolts, and/or other like threadedfasteners passing through respective through holes 30 formed in thetrack shoe 24.

As shown in FIG. 2, the track shoe 24 may include a substantially planarbase 28, and a ground-engaging surface 26 opposite the base 28. In eachof the embodiments discussed herein, the base 28 may be disposed on afirst side of the track shoe 24, and the ground engaging surface 26 maybe disposed on a second side of the track shoe 24 opposite the firstside. The base 28 may be configured to mate with one or more track linksand/or other components of the track 20 described above. The groundengaging surface 26, on the other hand, may be configured to act on awork surface of the worksite or other environment in which the machine10 is employed.

As discussed above, the track shoe 24 may include one or more thru holes30 extending from the ground engaging surface 26 to the base 28. Thethru holes 30 may be shaped, sized, located, and/or otherwise configuredto accept a corresponding fastener (not shown), and such fasteners mayassist in coupling the track shoe 24 to one or more track links. Thetrack shoe 24 may also include one or more passages 60 extending fromthe ground engaging surface 26 to the base 28. The passages 60 may beuseful in permitting, for example, dirt, mud, stones, water, and/orother like work surface materials to pass therethrough during operationof the track 20. Although the passages 60 are illustrated in FIG. 2 asbeing substantially rectangular, in other exemplary embodiments, thepassages 60 may be substantially oval shaped, substantially round,and/or any other shape, size, and/or configuration to facilitate passageof such materials during operation of the track 20. Such passages 60 maybe of like size, shape, and/or configuration, or as shown in FIG. 2, afirst passage 60 may have a different shape, size, and/or configurationthan a second passage 60 of the track shoe 24. For instance, a firstpassage 60 may be larger than a second passage 60 of the track shoe 24.Each of the passages 60 may be positioned proximate the center of thetrack shoe 24, proximate edges thereof, and/or at any other locationsalong the ground engaging surface 26 of the track shoe 24 to facilitatepassage of work surface materials therethrough.

The track shoe 24 may also include one or more cutouts 58 disposedproximate a trailing edge 38 thereof. Cutouts 58 may be substantiallyU-shaped, substantially square, substantially rectangular, and/or anyother like shape. Such cutouts 56 may be configured and/or positioned tofacilitate passage of any of the work surface materials discussed abovetherethrough. In addition, the cutouts 58 may be configured to accept aportion of the chain 22 (FIG. 1) during operation of the track 20. It isunderstood that the cutouts 58, passages 60, and/or other elements ofthe track shoe 24 may be formed through mechanical cutting, lasercutting, scribing, milling, drilling, and/or any other known process. inadditional exemplary embodiments, the track shoe 24 may be forged orcast, and in such exemplary embodiments, one or more of cutouts 58and/or passages 60 may be formed in the track shoe 24 during such aprocess. In still further exemplary embodiments, an ingot or bloom ofdesired material may be rolled and/or otherwise formed into lengthshaving a desired track shoe profile. Such rolled lengths may be referredto as “special sections,” and such special sections may have lengths ofup to 100 ft, or longer. In exemplary embodiments, individual trackshoes 24 may be cut from the rolled special sections. The cutouts 58,passages 60, and/or other elements of the track shoes 24 may then beformed in the individual track shoes 24 through cutting, drilling,etching, and/or other known processes.

The track shoe 24 may be formed from any metal known in the art such as,for example, steel, aluminum, and/or alloys thereof. In an exemplaryembodiment, the entire track shoe 24 may be formed from a singlematerial. In additional exemplary embodiments, one or more portions ofthe track shoe 24 may be formed from a first material, and a remainderof the track shoe 24 may be formed from a second material different fromthe first material. In such exemplary embodiments, the various differentportions of the track shoe 24 may be coupled together through welding,mechanical coupling, and/or other known joining processes.

In additional exemplary embodiments, the track shoe 24 may be formedfrom a relatively low mass, high yield strength material such as, forexample, SAE 15B34 steel, SAE 40BV40 steel, SAE 15B27 steel, and/orother like materials. Such materials may be hardened through claddingand/or other known material hardening processes to further increaseyield strength. As used herein, the term “yield strength” means thedegree to which the track shoe 24 may be subjected to a constant loadbefore becoming permanently deformed. A track shoe having a higher yieldstrength will be capable of greater deflection before suffering apermanent deformation than a track shoe having a relatively lower yieldstrength. For example, SAE 15B34, SAE 40BV40, and/or SAE 15B27 steel mayhave a higher carbon content than standard track shoe steels, therebyresulting in a relatively higher yield strength, greater hardness, andimproved resistance to wear. In exemplary embodiments, such high carboncontent steels may have a carbon content greater than approximately 0.3%by weight, whereas standard track shoe steels may have a carbon contentless than 0.3%.

As shown in FIG. 2, the ground engaging surface 26 may include one ormore grouser bars. For example, the ground engaging surface 26 of thetrack shoe 24 may include first and second grouser bars 32, 33, and inan exemplary embodiment, the ground engaging surface 26 of the trackshoe 24 may also include a third grouser bar 34. Each of the grouserbars 32, 33, 34 may be substantially parallel to one another, and eachgrouser bar 32, 33, 34 may be disposed along a width D3 of the trackshoe 24. In further exemplary embodiments, at least two of the grouserbars 32, 33, 34 may be non-parallel. The shape, size, and location ofeach of the grouser bars 32, 33, 34 may improve performance of the trackshoe 24, in particular, the height, width, and/or location of eachgrouser bar 32, 33, 34 may maintain and/or increase the yield strengthof track shoes 24. The greater the overall size of the grouser bar 32,33, 34, the greater the yield strength of the resulting track shoe 24.Such grouser bar configurations may also enable the thickness and/ormass of high carbon content track shoes 24 to be decreased throughvarious other modifications to the track shoes 24.

For example, utilization of high carbon content steels such as, forexample, SAE 15B34, SAE 40BV40, and/or SAE 15B27 steel to form the trackshoe 24 may allow for the use of grouser bars having reduced height andwidth as compared to conventional grouser bars, without compromising theyield strength of the resulting track shoe 24. The reduced dimensions ofthe grouser bars 32, 33, 34 may, in turn, reduce the overall mass andcost of manufacturing the track shoe 24. For example, track shoes madefrom standard low carbon content steels, and having standard sizedgrouser bars, may generally have a yield strength between approximately1205 Mpa and approximately 1960 Mpa, and may generally have a massgreater than approximately 20 kg. However, utilizing high carbon contentsteels such as, for example, SAE 15B34, SAE 40BV40, and/or SAE 15B27steel, in conjunction with the reduced grouser bar heights and widthsdiscussed herein, may result in a track shoe 24 having a substantiallyreduced mass while maintaining a yield strength between approximately1205 Mpa and approximately 1960 Mpa. In further exemplary embodiments,such track shoes 24 may have a yield strength between approximately 1000Mpa and approximately 2000 Mpa. The mass of the high carbon contenttrack shoes 24 described herein may be further reduced by minimizing thethickness of the track shoe 24. For example, such track shoes 24 mayhave a mass between approximately 10 kg and approximately 15 kg. Inexemplary embodiments, such track shoe 24 may have a mass less thanapproximately 12.8 kg, and in further exemplary embodiments, the trackshoe 24 may have a mass less than approximately 11.5 kg. The mass of thehigh carbon content track shoes 24 described herein may be betweenapproximately 10% and approximately 30% less than corresponding massesof similar track shoes made from standard track shoe steels.

As noted above, in order to achieve such reduced mass with track shoesformed from high carbon content steels without compromising theresulting yield strength of the track shoe 24, the grouser bars 32, 33,34 may be formed to have particular heights and/or widths. In exemplaryembodiments of the present disclosure, the respective heights and/orwidths of the grouser bars 32, 33, 34 may be substantially equal, whilein further exemplary embodiments, each grouser bar 32, 33, 34 may have adifferent respective height and/or width. For example, as shown in FIG.3, the first grouser bar 32 may have a width W1 between approximately21.2 mm and approximately 24.8 mm. In such an exemplary embodiment, thesecond grouser bar 33 may have a width W2 between approximately 14.4 mmand approximately 17.6 mm. In addition, in such an exemplary embodiment,the third grouser bar 34 may have a width W3 between approximately 15.8mm and 16.2 mm. In further exemplary embodiments, at least one of thegrouser bars 32, 33, 34 may have a width between approximately 12.6 mmand approximately 14.2 mm. In still further exemplary embodiments, atleast one of the grouser bars 32, 33, 34 may have a width betweenapproximately 10 mm and approximately 50 mm. These dimensions, whileminimizing the overall mass of the high carbon content track shoe 24,may also maintain a yield strength of the track shoe 24 betweenapproximately 1205 Mpa and approximately 1960 Mpa.

As shown in FIG. 2, the ground engaging surface 26 may include at leastone substantially planar flat 44, and the flat 44 may be disposedadjacent to at least one of the grouser bars 32, 33, 34. For example,the ground engaging surface 26 may include a first substantially planarflat 44 disposed between the first and second grouser bars 32, 33, and asecond substantially planar flat 46 disposed between the second andthird grouser bars 33, 34. At least one of the flats 44, 46 may also bedisposed along the width D3 of the track shoe 24. Each of the grouserbars 32, 33, 34 may include a respective first and second side wall 50,52, and each of the widths W1, W2, W3 may extend between the respectivefirst and second side walls 50, 52. As shown in FIG. 3, such sidewalk50, 52 may extend upward from and substantially perpendicular to atleast a portion of the ground engaging surface 26.

In such exemplary embodiments, the height of each grouser bar 32, 33, 34may also be measured from at least one of the flats 44, 46. For example,as shown in FIG. 3, a height H1 of the first grouser bar 32 may bebetween approximately 18.5 mm and approximately 21.5 mm, and the heightH1 may extend from the flat 44 to a top surface 48 of the grouser bar32. In such an exemplary embodiment, a height H2 of the second grouserbar 33 may be between approximately 19.5 mm and approximately 22.5 mm,and the height H2 may extend from the flat 46 to a top surface 48 of thesecond grouser bar 33. Moreover, a height H3 of the third grouser bar 34may be between approximately 20 mm and approximately 23 mm, and theheight H3 may extend from the flat 46 to a top surface 48 of the grouserbar 34. In further exemplary embodiments, at least one of the grouserbars 32, 33, 34 may have a height less than approximately 26 mm. Instill further exemplary embodiments, at least one of the grouser bars32, 33, 34 may have a height between approximately 10 mm andapproximately 130 mm.

As shown in FIG. 3, the track shoe 24 may also include a leading edge 36opposite the trailing edge 38. The first grouser bar 32 may be disposedproximate the trailing edge 38, the third grouser bar 34 may be disposedproximate the leading edge 36, and the second grouser bar 33 may bedisposed between the leading edge 36 and trailing edge 38. Morespecifically, the first grouser bar 32 may be disposed between thetrailing edge 38 and the first flat 44, the second grouser bar 33 may bedisposed between the first and second flats 44, 46, and the thirdgrouser bar 34 may be disposed between the second flat 46 and theleading edge 36. In an exemplary embodiment, the first and third grouserbars 32, 34 may be spaced substantially equally from the second grouserbar 33. In addition, the second grouser bar 33 may be approximatelycentrally located along the ground engaging surface 26. For example, thetrack shoe 24 may have an overall length D2 between approximately 222.5mm and approximately 215.5 mm, and in an exemplary embodiment, theoverall length D2 may be equal to approximately 219 mm. In suchexemplary embodiments, a centerline 72 of the second grouser bar 33 maybe disposed at a distance D1 between approximately 96 mm andapproximately 92 mm from the leading edge 36. In such exemplaryembodiments, the centerline 72 of the second grouser bar 33 may bedisposed, for example, at a distance approximately 94 mm from theleading edge 36. In further exemplary embodiments, like centerlines 70,74 of the first and third grouser bars 32, 34 may be spaced anydesirable distance from the centerline 72 of the second grouser bar 33.For example, the centerlines 70, 74 of the first and third grouser bars32, 34 may be substantially equally spaced from the centerline 72 of thesecond grouser bar 33. Alternatively, the first and third grouser bars32, 34 may each be disposed at different distances from the secondgrouser bar 33. Such spacing may be determined through, for example,finite element analysis to maximize the yield strength of the resultingtrack shoe 24 given the additional dimensional and/or materialcomposition constraints of the track shoe 24 described herein. Forexample, through finite element analysis, it has been determined thatspacing the centerline 70 of the first grouser bar 32 from thecenterline 72 of the second grouser bar 33 by approximately 72.5 mm, andspacing the centerline 74 of the third grouser bar 34 from thecenterline 72 of the second grouser bar 33 by approximately 73.7 mm,maintains the yield strength of the resulting high carbon content trackshoe 24 having the grouser bar widths W1, W2, W3 and heights H1, H2, H3discussed herein between approximately 1205 Mpa and approximately 1960Mpa.

In exemplary embodiments, the first flat 44 may include a widthextending between the second sidewall 52 of the first grouser bar 32 andthe first sidewall 50 of the second grouser bar 33. Additionally, thesecond flat 46 may include a width extending between the second sidewall52 of the second grouser bar 33 and the first sidewall 50 of the thirdgrouser bar 34. In such exemplary embodiments, the widths of the firstand second flats 44, 46 may be approximately equal. In such exemplaryembodiments, the width of at least one of the first and second flats 44,46 may comprise approximately one quarter of the overall length D2 ofthe track shoe 24, and the combined width of the first and second flats44, 46 may comprise approximately half of the overall length D2. Inaddition, the width W1 of the first grouser bar 32 may be approximatelyhalf of the width of at least one of the first and second flats 44, 46.Moreover, the combined width of the first, second, and third grouserbars 32, 33, 34 may be approximately equal to the width of at least oneof the first and second flats 44, 46. Accordingly, the combined width ofthe first, second, and third grouser bars 32, 33, 34 may compriseapproximately one quarter of the overall length D2. In exemplaryembodiments in which the centerline 70 of the first grouser bar 32 isspaced from the centerline 72 of the second grouser bar 33 byapproximately 72.5 mm, and the centerline 74 of the third grouser bar 34is spaced from the centerline 72 of the second grouser bar 33 byapproximately 73.7 mm, the width of the first flat 44 may beapproximately 51.3 mm and the width of the second flat 46 may beapproximately 56.8 mm.

The track shoe 24 may also include a substantially rounded tip 68 at theleading edge 36. The tip 68 may have any desirable radius in order toassist in, for example, reducing clearance between the leading edge 36of the track shoe 24 and a trailing edge of an adjacent track shoecoupled to the track 20. The track shoe 24 may also include asubstantially horizontal shelf 66 adjacent the tip 68 on the groundengaging surface 26. The shelf 66 may, for example, connect the tip 68to the side wall 52 of the third grouser bar 34. In an exemplaryembodiment, the ground engaging surface 26 between the sidewall 52 andthe shelf 66 may be rounded so as to include a desirable radius R5. Sucha radius R5 may also assist in, for example, reducing clearance betweenadjacent track shoes during use.

The overall thickness of the track shoe 24 may be selected to assist inreducing the mass of the track shoe 24, while maintaining sufficientyield strength for excavation and/or other track shoe applications. Asshown in FIG. 3, such a thickness T may be measured between the groundengaging surface 26 and the base 28. In particular, the track shoe 24may include such a thickness T extending from the first and second flats44, 46 of the ground engaging surface 26 to corresponding substantiallyplanar flats 62, 64 of the base 28. It is understood that one or more ofthe flats 44, 46, 62, 64 may be disposed along substantially the entirewidth D3 of the track shoe 24. In an exemplary embodiment, the thicknessT may be a thickness of at least one of the flats 44, 46, and thethickness T may be between approximately 6.5 mm and approximately 8.5mm. In another exemplary embodiment, the thickness T may be betweenapproximately 5 mm and approximately 30 mm. In additional exemplaryembodiments, the thickness T may be approximately 7.5 mm.

In exemplary embodiments, the base 28 may include one or more reliefs40, 42 shaped, sized, and/or disposed to reduce the mass of the trackshoe 24 without significantly decreasing the yield strength thereof. Forexample, such reliefs 40, 42 may be shaped, sized, and/or disposed onthe base 28 to minimize the amount of material used in forming the trackshoe 24 without resulting in a corresponding decrease in the yieldstrength. The yield strength of the track shoe 24 is primarily dependentupon the material used to form the track shoe 24, and the height, width,and relative positions of the grouser bars 32, 33, 34. Forming reliefs40, 42 by removing material from the base 28 opposite one or more of thegrouser bars 32, 33, 34, on the other hand, has relatively little effecton the resulting yield strength of the track shoe 24. Accordingly, for arelatively large grouser bar, a correspondingly large relief may bedisposed on the base 28 opposite the grouser bar without adverselyreducing yield strength of the track shoe. In exemplary embodiments, thereliefs 40, 42 may be disposed such that the centerline 70 of the firstgrouser bar 32 is collinear with a centerline of the first relief 40 andthe centerline 72 of the second grouser bar 33 is collinear with acenterline of the second relief 42.

As shown in FIG. 3, just as each of the grouser bars 32, 33, 34 may havea unique shape and/or size, the corresponding reliefs 40, 42 may alsohave unique shapes and/or sizes. The shapes and/or sizes of the reliefs40, 42 may, however, correspond to the shapes and/or sizes of thegrouser bars 32, 33, 34 opposite from which the reliefs 40, 42 areformed. For example, the first relief 40 may have a first radius R1, andthe second relief 42 may have a second radius R2 less than the firstradius R1. The smaller radius R2 of the second relief 42 may correspondto the smaller height and/or smaller width W2 of the second grouser bar33 relative to the corresponding dimensions of the first grouser bar 32.In exemplary embodiments, the first radius R1 may be betweenapproximately 11 mm and approximately 12 mm, and the second radius R2may be between approximately 4 mm and 5 mm. In further exemplaryembodiments, the first radius R1 may be approximately 11.3 mm and thesecond radius R2 may be approximately 5 mm. In exemplary embodiments,the reliefs 40, 42 may be disposed opposite corresponding grouser bars32, 33, along substantially the entire width D3 of the track shoe 24.

The base 28 may also include a curved portion 54. The curved portion 54may be disposed along substantially the entire width D3 of the trackshoe 24 opposite the third grouser bar 34. The curved portion 54 mayhave any desirable radius R3, and the radius R3 may be chosen to reduceclearance between the track shoe 24 and a trailing edge of an adjacenttrack shoe (shown in FIG. 3). In an exemplary embodiment, the radius R3may be between approximately 54 mm and approximately 58 mm, and in afurther exemplary embodiments, the radius R3 may be approximately 56.5mm.

The ground engaging surface 26 may also include one or more curvedportions, and in an exemplary embodiment, the ground engaging surface 26may include a curved portion 56 adjacent to the first grouser bar 32 andproximate the trailing edge 38 of the track shoe 24. In an exemplaryembodiment, the curved portion 56 of the ground engaging surface 26 mayhave a radius R4 that is substantially equal to the radius R3 of thecurved portion 54. Such a radius R4 may assist in reducing, for example,clearance between adjacent track shoes 24. In still further exemplaryembodiments, the radius R3 of the curved portion 54 may be differentfrom the radius R4 of the curved portion 56. For example, the radius R3of the curved portion 54 may be approximately 56.5 mm, and the radius R4of the curved portion 56 may be approximately 55 mm.

INDUSTRIAL APPLICABILITY

The track shoes 24 of the present disclosure may be applicable to anytrack type mobile machine. The disclosed track shoes 24 may have greaterhardness and/or yield strength characteristics relative to standardsteel track shoes, thereby improving durability of the undercarriage 12.Further, the track shoes 24 of the present disclosure may loweroperating cost of the mobile machine 10 by utilizing less material toform such track shoes 24, and may result in fuel savings due to reducedundercarriage mass. Each of these benefits may be achieved through theuse of the high carbon content steels described above in conjunctionwith the unique geometry and relative placement of the grouser bars 32,33, 34 and reliefs 40, 42.

For example, the formation of reliefs 40, 42 on the base 28 of the trackshoes 24 made from a high carbon content, high yield strength steel,such as SAE 15B34, SAE 40BV40, and/or SAE 15B27 steel, may assist inreducing the resulting mass of the track shoe 24 while maintaining adesired yield strength. Thus, while the reliefs 40, 42 may add somecomplexity to the manufacturing process, the resulting track shoe may besuperior in operation to track shoes without such reliefs.

Moreover, forming the track shoes 24 of the present disclosure through arolling process may be less expensive than forming the track shoe 24through forging, casting, and/or other like processes. Such processesrequire re-heating cylindrical rods, rectangular plates, and/or otherlengths of semi-finished steel, and forming individual track shoes fromthe re-heated steel. Such processes are time consuming, labor intensive,and relatively costly. Rolling ingots or blooms of raw steel intolengths having the profile of the track shoes 24 described herein, onthe other hand, eliminates the need for such re-heating. Instead,rolling raw steel into special sections having a profile that includesthe reliefs 40, 42, grouser bars 32, 33, 34, flats 44, 46, 62, 64,and/or other portions of the track shoe 24 enables manufacturers tosimply cut individual track shoes 24 from the special sections. Thus,forming track shoes 24 through a rolling process eliminates the addedtime, labor, and expense associated with re-working semi-finished steel.

In addition, unlike forging or casting, rolling processes, such as hotrolling, form elongated longitudinal grains in the microstructure of thesteel. Such grains increase the strength, ductility, and toughness ofthe material. Hot rolling steels and other like materials also reorientsany impurities in the material, thereby creating “stringers” that arealigned substantially parallel to the rolled surface of the material.Such stringers are highly resistant to fracture and tend to furtherincrease the durability of the material. During the forging or castingprocess, on the other hand, such impurities are randomly oriented, andwhen intersecting with the surface of the material, such impurities canbe a propagation point for cracks. As a result, track shoes 24 formedfrom rolling processes, such as hot rolling, are more resistant to wearand typically have a longer useful life than track shoes formed fromother processes.

In exemplary embodiments, track shoes 24 of the present disclosure maybe coupled to track links of the undercarriage 12 via one or more of thethreaded fasteners, through holes 30, and threaded holes describedabove. A formed chain link 29 may then be joined to one or moreadditional like chain links 29 to form a completed chain 22. Such achain 22 may be incorporated into the track 20 of a machine 10 for anyof the uses described above.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed track shoes24. Other embodiments will be apparent to those skilled in the art fromconsideration of the specification and practice of the disclosedsystems. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

1-21. (canceled)
 22. A mobile machine track shoe having a leading edgeand a trailing edge, comprising: a ground engaging surface including: asubstantially planar flat, a first grouser bar extending substantiallyperpendicular to the flat and substantially parallel to the leading andtrailing edges, and a first curved portion disposed at the leading edge;and a base opposite the ground engaging surface, the base including: afirst relief disposed opposite the first grouser bar, and a secondcurved portion disposed at the trailing edge, wherein the first reliefhas a depth measured from the base to the deepest portion of the reliefthat is less than a thickness of the track shoe measured from the baseto the flat.
 23. The track shoe of claim 22, further including a secondgrouser bar oriented substantially parallel to first grouser bar. 24.The track shoe of claim 23, further including a second relief disposedopposite the second grouser bar.
 25. The track shoe of claim 23, whereinthe second grouser bar is disposed opposite the first curved portion.26. The track shoe of claim 23, further including a third grouser barsubstantially parallel to the first and second grouser bars and disposedproximate the leading edge.
 27. The track shoe of claim 26, wherein theflat is a first flat including a width extending between a sidewall ofthe first grouser bar and a first sidewall of the second grouser bar,the track shoe further comprising a second substantially planar flatincluding a width extending between a sidewall of the third grouser barand a second sidewall of the second grouser bar, wherein the widths ofthe first and second flats are approximately equal.
 28. The track shoeof claim 27, wherein a combined width of the first and second flatscomprises approximately half of an overall length of the track shoe. 29.The track shoe of claim 27, wherein a combined width of the first,second, and third grouser bars is approximately equal to the width of atleast one of the first and second flats.
 30. The track shoe of claim 22,wherein the first grouser bar has a first centerline and the firstrelief has a second centerline collinear with the first centerline. 31.The track shoe of claim 30, wherein the first relief is disposedopposite the first grouser bar along an entire width of the track shoe.32. The track shoe of claim 22, further including one or more thru holesextending from the ground engaging surface to the base.
 33. The trackshoe of claim 32, further including one or more elongated passagesextending from the ground engaging surface to the base.
 34. The trackshoe of claim 22, wherein the first curved portion has a first radiusand the second curved portion has a second radius less than the firstradius.
 35. A mobile machine track shoe having a leading edge and atrailing edge, comprising: a ground engaging surface including asubstantially planar flat, a first grouser bar extending substantiallyperpendicular to the flat and substantially parallel to the leading andtrailing edges, and a second grouser bar extending substantiallyparallel to the first grouser bar; and a base opposite the groundengaging surface, the base including a first relief disposed oppositethe first grouser bar wherein the first relief has a depth measured fromthe base to the deepest portion of the relief that is less than athickness of the track shoe measured from the base to the flat, andwherein the track shoe comprises steel having a carbon content greaterthan approximately 0.3%.
 36. The track shoe of claim 35, furtherincluding a third grouser bar substantially parallel to the first andsecond grouser bars and disposed proximate the leading edge.
 37. Thetrack shoe of claim 36, wherein a combined width of the first, second,and third grouser bars comprises approximately one quarter of an overalllength of the track shoe.
 38. The track shoe of claim 35, furtherincluding a first curved portion disposed at the leading edge, and asecond curved portion disposed at the trailing edge.
 39. The track shoeof claim 38, wherein the second grouser bar is disposed opposite thefirst curved portion
 40. The track shoe of claim 35, further includinglongitudinal grains formed in the microstructure of the steel.
 41. Atrack shoe for a mobile machine, comprising: a ground engaging surfaceincluding a first grouser bar, a second grouser bar substantiallyparallel to the first grouser bar, and a third grouser bar substantiallyparallel to the second grouser bar, wherein a combined width of thefirst, second, and third grouser bars comprises approximately onequarter of an overall length of the track shoe; and a base opposite theground engaging surface, the base including a first relief and a secondrelief substantially parallel to the first relief, wherein a centerlineof the first grouser bar is collinear with a centerline of the firstrelief and a centerline of the second grouser bar is collinear with acenterline of the second relief, and wherein the track shoe comprisessteel having a carbon content greater than approximately 0.3% andfurther includes longitudinal grains formed in the microstructure of thesteel.